It is sometimes desirable to use components with high current requirements in portable electronic apparatus. Problems arise, however with driving high-current devices using relatively low voltage power supplies, such as common batteries for example. On the one hand, battery voltage must be sufficient to drive the high-current devices. On the other hand, the current requirements may be so high that there is a risk of damaging the batteries. An example is the use of powerful LEDs as flash elements in small cameras. Overall, this is desirable in order to reduce battery drain, reduce cost, and minimize device size compared to xenon flash systems. Commonly available Lithium Ion (Li-Ion) batteries often used in such applications are limited in their voltage capacities, however, and are often incapable of withstanding the high currents required for driving the LEDs. One potential solution to the problem is to use the available batteries for charging capacitors capable of being charged to sufficient voltage levels and then in turn using the capacitors to drive the LEDs. In such instances it would be desirable to use a low-resistance switch to drive the LEDs if not for the following problems. The current has a tendency to change as the capacitors are discharged. The LEDs themselves can have significant processing variation, in turn yielding forward voltage variation. There is also a temperature coefficient associated with the forward voltage drop of the LEDs, which affects the charging performance.
Due to the foregoing and other problems and potential advantages, improved driver methods, particularly LED driver methods, would be useful contributions to the applicable arts.